App icons such as YouTube are not being displayed on the apps screen.

Note: As of the 20th of April 2015, Google's YouTube app will no longer be supported on certain Sony products. You can find out more via this official statement from Google.

Regrettably we are unable to offer a solution for this termination of service on the affected models themselves. However, there are still plenty of ways for you to enjoy watching YouTube. You can find out more solutions to access YouTube

Make sure that the TV is connected to the Internet, and then refresh the Internet content.